Heathrow airport saw a record 1.3 million passengers during its busiest August week last year, and 2025 is set to surpass this, with UK airports preparing for their ‘busiest-ever summer’.
The overlap between late-summer leisure travel and the return of international business trips has made August one of the tightest windows for booking affordable flights.
To find out where travellers are paying the steepest premiums, we’ve analysed top city destinations around the world to determine where UK travellers are most likely to pay the steepest peak price penalty this August.
Oslo takes the top spot for peak price penalties
Travellers from the UK can expect to pay 453 percent more for their flights during the height of summer, costing £105 on average compared to just £19 in lower demand periods.
Despite Norway becoming more affordable to visit, flying to Oslo in peak summer remains a costly exception. Limited seat availability, compressed travel windows and a busier summer period all send airfares soaring to eye-watering highs.
Copenhagen narrowly misses first place
With a 452% surge in flight costs during the peak travel season, Copenhagen’s August fares are just a fraction lower than Oslo’s.
While flights to the Danish capital can be bought for as low as £23 during mid-September, travellers over August can expect to pay £127 on average.
Passenger numbers at Copenhagen Airport hit 2.95 million last August (up 13 percent year-on-year) despite fewer flights being available, which may be pushing prices up further.
Stockholm completes the Nordic price-hike trio
With a 326 percent August price increase, Stockholm completes the top three destinations with the steepest peak price penalty.
One-way fares jump from £27 to £115 in peak season, thanks to rising passenger demand at Sweden’s largest airport, Arlanda.
Montreal (212 percent) and Berlin (188 percent) complete the top five cities with the steepest peak price penalty.
Brits pay over twice as much for summer flights worldwide
But no matter the destination, UK travellers face a steep summer price surge.
On average, flights in August cost more than twice as much as in September, at a 105 percent increase across all cities analysed.
Whether travelling for business or leisure, sometimes flying during the busy period is unavoidable. But even if you’re tied to travelling in August, there are still ways to avoid the worst of the price hikes.
Flying just a day or two later, avoiding weekend departures and booking early can help keep costs down, especially for families and business travellers trying to stretch budgets.
For companies managing essential summer trips, visibility and planning are key. Partnering with a travel management expert can make all the difference when availability is tight and prices are at their peak.
If you’d like to view the data for all 40 cities analysed in this study, you can do so here.
Methodology
For this study, we used Google Flights to analyse how flight prices change during busy travel periods compared to quieter times.
We searched for the lowest one-way fares from London Heathrow to a selection of major international business travel destinations and compared the cost over specific peak and post-peak travel dates. These were:
- Peak summer holidays – 9th August 2025
- Post-peak summer holidays – 13th September 2025
We then ranked the cities on the percentage by which their costs increase at peak times.